To summarize: Trump has a real history of telling lies in order to maximize fossil fuel extraction and consumption. Harris has helped take at some action in the direction of getting the US off of fossil fuels though not yet enough.
I’m very much in favor of stopping Trump, so if you want to help out, you can do that here
To be fair to her, I don’t think her views have actually constituted the limiting factor on US action — that would have been what could pass through the Senate, where we needed the vote of a literal coal baron to get even budget reconciliation passed (that takes only 50 votes + the VP, anything else requires 60 votes)